Html.TagHandler not detecting certain HTML tags

Question

I am writing my own tag handler (below). For some reason, it does not detect certain tags, like <blockquote>, or <a> as unsupported.

When I debug at the line if(!SUPPORTED_HTML_TAGS.contains(tag.toLowerCase())), passing in HTML containing <blockquote> and <a>'s in it, I don't even see the or tags being detected there. I only see tag appear as "html", and "body". I do see it detect <table>, <tr>, <td> though.

Is this a known issue/bug?

private static class RichTextEditorTagHandler implements Html.TagHandler
{
    private final List<String> SUPPORTED_HTML_TAGS =
        Arrays.asList("html", "body", "b", "i", "u", "br", "p", "div", "span");
    private static boolean hasUnsupportedHtml;

    @Override
    public void handleTag(boolean opening, String tag, Editable output, XMLReader xmlReader)
    {
        if (!SUPPORTED_HTML_TAGS.contains(tag.toLowerCase()))
            hasUnsupportedHtml = true;
    }
}